Metasequoia (Cupressaceae)


Sequoia (l) Metasequoia (r)
UofAz Palynology


Drawing O.K.Davis
UofAz Palynology


Sequoia sempervirens
U.C. Berkeley San Francisco Estuary pollen

Plant:
Deciduous conifer tree 20 - 30 m high, needles ca. 15 mm long. Female cone ca. 2.5 cm diameter, male cones in pendant racemes. In the early 20th century, the entire population of Metasequoia glyptostoroboides consisted of just a few thousand trees in the Sichuan, Hubei, and Hunan provinces of China. By 1948, seeds from a single grove along the Yangtze River had produced 1500 seedlings in Europe and the USA. These populations are of very low genetic diversity, and are therefore of low fertility. Thanks to the recent cooperation of Chinese botanists, new genetic stock has been introduced to the USA and European populations.

Pollen light micrograph:
The grain is about 30 µm in diameter and somewhat thickened on the anti-papillate 2/3 of the grain. Occasionally a ridge or rim sepparates the thick and thin portions of the grain. The pollen of Metasequoia glyptostroboides (Dawn Redwood) is similar to that of the other taxodiaceous grains (Taxodiaceae and Cupressaceae are combined in recent floras, even though their pollen is distinct).

Papillate Inaperturate Conifer Pollen
After Erdtman, 1957.
Cephalotaxus
Cryptomeria
Glyptostrobus
Metasequoia
Nothotaxus
Saxegothaea
Sciadopitys
Sequoia
Sequoiadendron
Tiwania
Taxodium

Pollen scanning electron micrograph (SEM)

Production and Dispersal:
Wind pollinated with moderate production and dispersal (?).

Preservation:
Moderate to poor preservation (?).

Fossil Occurrence:
Metasequoia glyptostoroboides is a "living fossil" whose foliage is common in late-Cretaceous through Pleistocene sediments of the Northern Hemisphere, particularly in the early-Tertiary of the Arctic.

References:
    Erdtman, G. 1957.
    Pollen and Spore Morphology / Plant Taxonomy. Gymnospermae, Pteridophyta
    Bryophyta. Almqvist abd Wiksell. Stockholm.

Links

Owen K. Davis 12/99